Kasei Valles and Sacra Fossae

Mars Express flew over the boundary between Kasei Valles and Sacra Fossae and the High-Resolution Stereo Camera (HRSC) operated by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) imaged the region, acquiring spectacular views of the chaotic terrain in the area.
The images are centred at 12°N, 285°E and have a ground resolution of about 21 metres per pixel. They cover 225 kilometres by 95 kilometres or 21,375 square kilometres, an area roughly half the size of the Netherlands.

The images show an old 35-kilometre diameter impact crater in the north. The crater’s southwestern rim is heavily eroded. The erosion was caused primarily by flowing water. The source of the water was located in Echus Chasma, which lies roughly 850 kilometres to the southwest.

The crater floor and the northwestern part of the imaged region are remarkably flat and have been formed by sediments and basaltic lava flows originating from the Tharsis volcanic region.

The lower part of the image clearly shows the boundary between the smooth, lightly cratered plain, and the area with numerous fracture zones. Most of the fractures along the boundary are parallel to the edge of the Lunae Planum.

Several fracture zones are also visible in the western part of the image. Areas up to 10-kilometre across that experienced ‘subsidence’ (gradual compaction and sinking due to the weight of the layers) are still intact.